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EECS – Prof. A. Casalegno – 5th February 2018 1 Basic Part (3 points per questions, minimum score 12) 1. Write the Nernstian equilibrium potential for an electrochemical cell based on H2/O2 as a function of chemical activities 2. Depict the polarization curve of a PEM electrolyzer with reasonable values 3. Define the efficiency for a battery, indicating how SoC varies 4. Write an example of electrochemical reactions occurring in a Lithium-ion battery and the typical operating voltage range Name _____________________________ Person N. __________________________ EECS – Prof. A. Casalegno – 5th February 2018 2 Exercise 1 A PEM fuel cell operates at 80°C with high excess of pure H2 and O2, supplying at 0.8 V a current density equal to 1 A/cm2. Assuming that: 1. anode behaves as an ideal H2 electrode ( =0) 2. ion and mass transport effects in catalyst and diffusion layers are negligible 3. chemical activities of H2 and O2 are close to 1 4. membrane ion conductivity and thickness are respectively 0.05 S/cm and 50 μm 5. transfer coefficient of ORR is equal to 0.5 Estimate the voltage feeding high excess of air with O2 chemical activity equal to 0.17. Exercise 2 A Li-ion battery with nominal capacity of 7 Ah operates at ambient pressure and temperature, supplying 3.4 V during discharge at SoC=50% and C-rate=2. Assuming that: 1. Tafel kinetics is valid for both electrodes 2. ion and mass transport effects in electrodes are negligible 3. chemical activities of reactants are close to the value of SoC 4. electrolyte resistance is equal to 0.02 Ω 5. transfer coefficients of both electrodes during discharge are equal to 0.5 Estimate the voltage at SoC=75% and C-rate=1. EECS – Prof. A. Casalegno – 5th February 2018 3 Intermediate Part (3 points per questions) 1. Write the…